/****************************************************************************
 *
 * Copyright 2019 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/
/****************************************************************************
 * os/binfmt/libelf/libelf_read.c
 *
 *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <tinyara/config.h>

#include <sys/types.h>
#include <stdint.h>
#include <unistd.h>
#include <string.h>
#include <debug.h>
#include <errno.h>

#include <tinyara/fs/fs.h>
#include <tinyara/binfmt/elf.h>

#ifdef CONFIG_COMPRESSED_BINARY
#include <tinyara/binfmt/compression/compress_read.h>
#endif

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

#undef ELF_DUMP_READDATA		/* Define to dump all file data read */

/****************************************************************************
 * Private Constant Data
 ****************************************************************************/

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: elf_dumpreaddata
 ****************************************************************************/

#if defined(ELF_DUMP_READDATA)
static inline void elf_dumpreaddata(FAR char *buffer, int buflen)
{
	FAR uint32_t *buf32 = (FAR uint32_t *)buffer;
	int i;
	int j;

	for (i = 0; i < buflen; i += 32) {
		syslog(LOG_DEBUG, "%04x:", i);
		for (j = 0; j < 32; j += sizeof(uint32_t)) {
			syslog(LOG_DEBUG, "  %08x", *buf32++);
		}

		syslog(LOG_DEBUG, "\n");
	}
}
#else
#define elf_dumpreaddata(b, n)
#endif

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: elf_read
 *
 * Description:
 *   Read 'readsize' bytes from the object file at 'offset'.  The data is
 *   read into 'buffer'.
 *
 * Returned Value:
 *   0 (OK) is returned on success and a negated errno is returned on
 *   failure.
 *
 ****************************************************************************/

int elf_read(FAR struct elf_loadinfo_s *loadinfo, FAR uint8_t *buffer, size_t readsize, off_t offset)
{
	ssize_t nbytes;				/* Number of bytes read */
#if !defined(CONFIG_COMPRESSED_BINARY)
	off_t rpos;					/* Position returned by lseek */
#endif

	/* Advance offset by binary header size, loadinfo->offset will be 0 in normal exec call */
	offset += loadinfo->offset;

	/* Loop until all of the requested data has been read. */

	while (readsize > 0) {
#if defined(CONFIG_ELF_CACHE_READ)
		/* Cache only if readsize request <= cache block size */
		if (readsize <= CONFIG_ELF_CACHE_BLOCK_SIZE) {
			nbytes = elf_cache_read(loadinfo->filfd, loadinfo->offset, buffer, readsize, offset - loadinfo->offset);
		} else
#endif
		{
#ifdef CONFIG_COMPRESSED_BINARY
			nbytes = compress_read(loadinfo->filfd, loadinfo->offset, buffer, readsize, offset - loadinfo->offset);
#else
			/* Seek to the next read position */

			rpos = lseek(loadinfo->filfd, offset, SEEK_SET);
			if (rpos != offset) {
				int errval = get_errno();
				berr("Failed to seek to position %lu: %d\n", (unsigned long)offset, errval);
				return -errval;
			}

			/* Read the file data at offset into the user buffer */
			nbytes = read(loadinfo->filfd, buffer, readsize);
#endif
		}

		if (nbytes < 0) {
			/* EINTR just means that we received a signal */

			if (nbytes != -EINTR) {
				berr("Read from offset %lu failed: %d\n", (unsigned long)offset, (int)nbytes);
				return nbytes;
			}
		} else if (nbytes == 0) {
			berr("Unexpected end of file\n");
			return -ENODATA;
		} else {
			readsize -= nbytes;
			buffer += nbytes;
			offset += nbytes;
		}
	}

	elf_dumpreaddata(buffer, readsize);
	return OK;
}
